This invention relates to pressure transducers for use in internal combustion engine exhaust gas recirculation (EGR) systems and is particularly suited for use in those EGR systems which incorporate vacuum operated devices for controlling EGR. The invention relates particularly to devices employing carburetor venturi vacuum or suction as a source of signal pressure for controlling EGR. Venturi suction provides a pressure signal indicative of engine air mass flow and is a convenient signal source having characteristics which vary in the opposite sense of engine induction manifold depression. Where it is desired to control EGR as a function of air mass flow venturi suction can be readily utilized. More particularly the invention relates to EGR controllers responsive to venturi suction or venturi vacuum transducers as they are known.